Abstract

Giant rockslides and slumps are recognized over a large part of the east limb of the Sinking Creek anticline, a southern Appalachian fold. The slides are among the largest such features known in the Appalachians and are found within 15 km of the active Giles County, Virginia, seismic zone. The zone of rockslides, identified by anomalous topography and geologic structures, is about 25 km long and 1.0 km wide. Downslope transport, ranging from 0.5 to 1.0 km, of at least 100 million m3 of Silurian sandstones and shales can be identified. During sliding, bedding within individual blocks, as much as 5.0 km long, has undergone 30° to 90° rotation about a horizontal axis. The displaced masses have undergone extensive erosion and dissection and may be only remnants of previously more extensive slides. Secondary features associated with the rockslides include breakaway scarps, slope reversals, sag ponds, and slide breccias.

The recognition of these features, which might be mistaken for remnants of an Alleghanian thrust sheet, suggests that examination of similar settings throughout the southern and central Appalachian Valley and Ridge province might disclose additional examples of large ancient rockslides.

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